The present invention relates to device for propelling a vessel, such as a submarine, through water. More particularly, this invention relates to a highly efficient propulsion device which desirably results in little, if any, cavitation.
Those skilled in the art of propelling ships and submarines through water have long recognized the desirability of a highly efficient non-cavitating propulsion device. The more complicated the propulsion system the greater the possibility of mechanical failure. Water""s viscosity restricts movement of a vessel through the water. As a propeller pushes or pulls a vessel, bubbles begin to form on the low pressure surface of the propeller from cavitation and this cavitation alters the physics in the propeller""s function. Submarines conventionally must be operated at a very low speed to achieve little, if any, cavitation. The cavitation action itself also contributes to inefficiency of the propulsion device.
Numerous patents disclose pumps, including oscillating pumps and electromagnetically driven pumps. Many of these pumps are designed for a specific application. U.S. Pat. Nos. 2,815,715, 2,971,471, 3,074,351, 3,136,257, 3,215,084, 3,190,229, 3,836,289, 3,677,667, 3,839,983, 4,389,169, 4,787,823, 4,925,377, 5,085,563, 5,620,048, 5,567,131, and 5,115,930 disclose various types of pumps. Japanese reference 115906 and DE 3004109 are illustrative of non-U.S. pump patents. U.S. Pat. No. 4,076,467 discloses a pump having a tubular resilient pump element and one-way valve. The device has limited efficiency. Column 3 commencing at line 1 discloses an elastic tube which utilizes opposing helix reinforced filaments.
Prior art patents relating to propulsion systems for moving a vessel through water are disclosed in U.S. Pat. Nos. 2,056,475, 3,062,002 and 3,765,175. Devices specifically designed for powering boats include U.S. Pat. Nos. 3,826,217, 3,945,201, 4,026,235 and 4,031,844.
U.S. Pat. No. 5,298,818 discloses a thrust generator which utilizes superconducting magnets to push the fluid and thus propel the vessel through water. U.S. Pat. No. 5,333,444 discloses a superconducting electromagnetic thruster, and U.S. Pat. No. 5,717,259 discloses an electromagnetic machine which includes a rigid elongated hollow shell wrapped with wire which is connected to a power source. When current is flowing through the wire, the particles are attracted radially outward to deform the pouch.
The disadvantages of the prior art are overcome by the present invention, and an improved device is hereinafter disclosed suitable for propelling a vessel through water. The device is relatively simple in operation yet is both highly efficient and desirably results in little, if any, cavitation.
The present invention is directed to an propulsion device suitable for propelling a vessel, such as a submarine, through water. The device desirably results in little, if any, cavitation while propelling the device through water at a relatively high speed. Cavitation commonly occurs in a pump when the suction fluid is under a low pressure/high vacuum condition where the liquid turns into a vapor at the inlet of the device. This vapor is carried over to the discharge side of the device where it no longer xe2x80x9cseesxe2x80x9d vacuum and is compressed back into a liquid by the discharge pressure. This imploding action occurs violently and attacks the rotors, screws, gears, etc. that have been operating under a suction cavitation condition. Large chunks of material may be slowly removed from the exposed faces, thereby causing premature failure of the propulsion device. Cavitation occurs in a propeller or screw system when the water is xe2x80x9cpulled apartxe2x80x9d resulting in a noisy trailing foam that is easily detected both visually and auditory. The propeller cannot operate as efficiently in a foam environment as an uncavitated environment.
The propulsion device according to the present invention may utilize magnetic propulsion and contraction forces to change the length and thus the internal volume within a flexible bladder, which preferably is reinforced with a weave comprising fibrous reinforcing members. In an alternate embodiment, hydraulic power to cylinders is controlled to effect movement of the end caps and thereby cyclically change the volume of the inner chamber and the outer chamber which are separated by the bladder. Volume changes within the bladder and the volume changes between the bladder and the external housing are used to generate the propulsion forces. A clamshell device may be used to obtain reverse thrust.
To create compressive forces to move fluid, the device utilizes both an inner chamber and an outer chamber which each contribute to the filling and draining phase of the other. The device according to the present invention thus fills an outer chamber with water as the inner chamber is venting, then the device fills the inner chamber with water while the outer chamber is venting. This feature minimizes the pressure differential, which decreases the work and thus the effort needed for the propulsion device to function at a particular speed. Since the device does not require a suction action for filling the chamber, the contained water will not be subjected to gross negative forces that cause the gases to come out of solution. Water is then pressurized in the chambers and released to ambient pressure producing negligible cavitation. Since the device does not use a high differential between the filling pressure and the ambient pressure, the power generated is in propulsion.
It is a feature of the invention that the propulsion device may utilize valves which include polymer reeds that are in a tricuspid and/or bicuspid configuration similar to that of a human heart valve. Each valve in the device may be sized analogous to cardiac portions in the heart valve. The valves preferably are self-cleaning and quiet, and also have high efficiency and longevity.
It is a further feature of the invention that the material which provides the helix reinforcement may be formed of a carbon fiber, an aromatic polyamide fiber such as Kevlar, or currently advanced reinforcement which has significantly better fatigue properties than metal wire.
Another feature of the invention is that the propulsion device utilizes moving parts that are forgiving. In the event of failure of a valve, for example, the device may still propel through water.
The propulsion device according to the present invention is highly versatile; the length of stroke for the device may be full or partial.
A further feature of the invention is that the propulsion device utilizes attracting and repelling end caps and conventional sealing members, such as o-rings with reduced friction, to form reliable seals within the device. The device preferably utilizes ambient pressure and direction of motion to facilitate filling of the chambers.
Yet another feature of the invention is that the device may be electrically powered to change the magnetic attraction and repulsion of the end caps, or may be hydraulically powered to serve this same purpose.
An advantage of the invention is that the device is relatively simple and thus highly reliable. The further advantage of the invention is that the magnetic propulsion device will provide a relatively long life with few service problems.
These and further objects, features, and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings.